This invention relates generally to the utilization of a single electrically responsive vacuum regulating device to control a plurality of air control devices and, more specifically, to a system which utilizes an electric vacuum regulator to control the degree of vacuum supplied to an exhaust gas recirculation (EGR) valve and to an idle speed bypass valve.
Modern automobile engines must usually be maintained at sufficiently low engine speeds in order to lessen the amount of pollutants given off by the engine while it is idling. The idle speed bypass valve (idle air bypass valve or bypass valve) is utilized to set the engine idle speed as a function of the load on the engine. As is known, when vehicle accessories are switched on with the engine in an idling condition, the engine may stall. An example of idle speed bypass valves is illustrated in U.S. Pat. No. 4,388,856 which illustrates a pneumatic device which controls the positioning of a plunger which in turn is used to vary the position of the throttle mechanism to readjust the engine idle speed as a function of engine load.
In order to reduce exhaust gas emissions when the engine is off-idle, an exhaust gas recirculation valve has typically been used to recirculate a determinable percentage of the exhaust gas within an exhaust system of the engine into the intake manifold.
The controlling of engine idle speed and EGR recirculation conventionally utilized two separate and independent mechanisms to control these separate and independent functions. A modification of these earlier systems is shown by Yamaguchi in U.S. Pat. No. 4,281,631 which uses a single solenoid valve but still requires an electrically responsive changeover valve.
It is an object of the present invention to provide a system employing a single vacuum regulating device to selectively control the vacuum applied to a plurality of air control devices.
A further object of the present invention is to utilize a single vacuum regulating device to control the operation of an exhaust gas recirculation (EGR) valve and an idle speed bypass valve.
It is a further object of the present invention to provide a system for combined control of the above-identified valves which exhibits simple construction and efficient operation.
Accordingly, the invention comprises:
In a system including a throttle body communicating intake air to the intake manifold of an internal combustion engine, the throttle body housing a movable throttle plate, a vacuum responsive idle air bypass valve for bypassing intake air around the throttle plate and into the intake manifold, a vacuum responsive EGR valve for regulating the amount of exhaust gas permitted to be recirculated into the intake manifold, the improvement comprising means responsive to the position of the throttle plate for communicating vacuum manifold pressure to one of either of the EGR valve or the idle air bypass valve and for communicating atmospheric pressure to the other EGR valve or idle air bypass valve; means communicated to a vacuum input port on each of idle air bypass valve and EGR valve for varying the degree of manifold vacuum communicated thereto.